Mineral oil composition



Patented Feb. 11, i948 2.43am mm on. COMPOSITION George IL- S. Snyder,Woodbury, Ralph V. White, Pitman, John 1!. Bishop, Wenonah, and JohnSocoloisky, Woodbnry, N. 1., assignors to Snoo y-Vacuum Oil Company,

corporation of New York Application February 27, 1945, Serial No.580,074

. No Drawing.

1 Claims. This invention has to do with lubricants and. moreparticularly, has to do with lubricants for ferrous metal surfaces in anenvironment where such surfaces are-also subject to contact with waterand in consequence are likely to rust.

As is well known to those familiar with the art. difnculties have beenexperienced during the operation of steam turbines and particularlyduring the initial operation of new steam turbines because of therustingof the ferrous metal parts. The combination of fresh (not previouslyused) oil, clean new metal surfaces, and moist OOIldl-r tions ofoperation of new steam turbines appears to be particularly conducive torusting difllculties. Particles of rust depositedon or carried tobearing surfaces of small clearance such as the governor, for example,tend to cause sticking which renders them inoperative. In cases ofsevererusting bearings may be. injured.

The aforesaid rusting phenomenon is evidently the result of improper or.inadequateflwetting" of we metal'surfaces with oil thus permittingapreferential contact of the" surfaces with the water which is present.'Numerous materials have been proposed for use in suchoils to counteractthe inadequate "wetting" effect: unfortunately, however, such materialshave generally Incorporated, a

from six to eight carbon atoms substituted for the carboxylic hydrogenatoms of malic acid and being present in the mixture in a molar quantityof from about 40% to about 80%, and another of 'said esters having twolong-chain aliphatic lar proportions ofa short-chain aliphatic group andof a long-chain aliphatic group of the type given rise tootherrundesirable phenomena. For

example,'many organic esters which have been suggested for use inturbine oils and-the like to correct the rusting action normallycharacteris tic thereof,have proven to be undesirable inasmuch as theyformemulsions' withlthe oiland are used. As'iis well known.'emulsionss'eriously reduce or impair the high 1 degree of lubricatingwater present in theenvironment in which they efficiency required-inturbine operation andare to be religiously avoided. Typical of theorganic esters which inhibit ther'ustin'g action of turbine oilsand thelike but whichgive rise to emulsions are those obtained by reaction ofalcohols and oxy-polycarboxylic acids; representative of such esters isdioleyl malate.

The present invention is directed to an outstanding mineral oil. whichis substantially free from the aforesaid rusting'and emulsion difliculdefined above; and those oils which contain a:

mixture ofmalic estersin'which one of the said esters has twoshort-chain aliphatic groups and another of said esters has two.long-chain aliphatic groups of the type defined above, the

esters being presentin the mixture in .equimolecular proportions. Itwill be apparent, therefore, that chemical and physicaimixtures of suchesters, characterized as described above. are co tem lated by thepresentinvention.

The short-chain aliphatic groups which contain from six to eight carbonatoms may be wholly saturated or partially saturated and may be eitherstraightor branched-chain or cyclic in structure, although a whollysaturated branchedchain group such as 2-ethyl hexylisjpreferred.Specific examples of such groupsyaren-hexyl, cyclohexyl, n-heptyl,n-'-octyl and the preferred 2-ethyl hexyl group. Correspondin y, long-'chain aliphatic groups which contain at least twelve carbon atoms, andpreferably from twelve to eighteen carbon atoms," may bewholly saturatedor partially saturated and may be either straightor branched-chain instructure and, of

such groups the normal, partially saturated group oleyl is preferred.Illustrative of such.

groups are lauryl, '7-ethyl-2-methyl undecyl, cetyl, oleyl and stearyl.It will be apparent to those familiar with the art that the foregoingaliphatic groupsmay be introduced into the malic esters contemplatedherein by reacting the corresponding alcohols with malic acid. It is tobe understood, however, thatsuch groups may be ties. The outstandingmineral oil of this invention comprisesja yisc'ous mineral oil havingin.

admixture therewith a small amount'of an ester of malic acid obtained'byreacting one molar equivalent of malic acid with fromabout 0.8 to about1.6 molar equivalents of. a short-chain alcohol havingfrom six toeightcarbon atoms and with from about 1.2 to about 0.4 molar equivalentof a long-chain alcohol "having atleast introduced by all otherproceduresknown in the errand tnat'the invention is not to'be limited inzany sense by the method of preparation of the twnlve'carbon atoms. The.present invention is also predicated upon the discovery of an oilsimilarly characterized comprising a viscous mineral oil containing asmall amount of a mixture of esters of malic acid, one of said estershaving two short-chain aliphatic groups containing said esters. l

The following-example is presented in order to clearly'demonstrate amalic ester of the type contemplated herein.

Example 'Malic acid .(20.1 grams: 0.15 mole), occncl (40.2 grams;- 0.15mole) predominantly oleyl alcohol and having a hydroxyl number, of 210,and 2-ethyl hexanol (23.5 grams;-- 0.18 mole) were. digested for 3%hours at -120 C. in afiask provided with-a reflux take-on. Inasmuch assome 2-ethyl hexanol distilled out of the reaction mixture into thereflux take-off during digestion, a 0.03 mole excess of 2-ethyl hexanolwas used in order to maintain a reaction mixture having substantiallyequal amounts of the said alcohols. Thereafter. toluene was added to thereaction mixture and the resultant mixture was then reiluxed at Mil-145C. for about 7 hours. During the latter period about 4.9 cc. of waterwas collected in the reflux take-off, evidencing the formation of theesterof malic acid. The reaction mixture was filtered. Toluene wasremoved from the filtrate obtained thereby. by heating under vacuum to amaximum liquid temperature oi 100 C. at 3 mm. pressure. The esterproduct oi malic acid thus obtained had a neutralization number (n. 11.)of 20 and is believed to be predominantly one'isomeric form or a mixtureof both isomeri forms of 2-ethyl hexyl, oleyl malate. It is probable,however. that small amounts of dioleyl malate and dim-ethyl hexyl)malate are present in the product.- a I The number 01' carbon atoms inthe aforesaid aliphatic groups and the proportions of the said groups inthe malic acid esters of this invention are critical and, it notmaintained, esters appreciably inferior to those desiredand contemplatedare obtained. Esters oi. malic acid obtained by departing from theaforesald critical limitations have been found to either fail as rustinhibitors, such as dio tyl malate mentioned above, or cause substantialand deleterlpus -emulsions to form in an environment containing oil andwater. This relationsh p is demonstrated hereinafter by rust andemulsion test results. a

To demonstrate the outstanding character of the oil compositionscontemplated herein, typical rust and emulsiontests were carried outwith a mineral oil, withblendsoi the mineral oild small amounts of malicesters of the typede" Ted hereinabove, and with blends of the mineraloil and small amounts of related, inferior malic esters. notcontemplated herein. The malic esters so tested are identified by theiracidity as measured by their neutralization numbers and by theircomposition interms of molar equivalents oi. short-chain aliphaticgroups and of long-chain aliphatic groups. l h e esters described in thetable below as malate mixtures are prepared in the manner shown inthe-example above wherein definite molar quantities of a long-chainalcohol and of a short-chain alcohol are used to esterii'y malic acid;and the esters, described in the table as physical mixtures" areobtained by blending acid with definite proportions of a short-chainester of thesame acid. The oil used is a blend oi solvent-refined,Mid-Continent residual stock with a 'fsolvent-reflned, Mid-ContinentRodessa distillate stock and has an A. P; I. gravity of 30.8, a flashpoint of 445 F. and an S. U. V. of 407.! seconds at 100 F.; and had inadmixture therewith, 0.2% o! 2,6-ditertiary butyl--methyl phenol, a wellknown antioxidant. The oil is suitablefor use in turbines and the like,and the tests run on the oil and oil blends simulate conditions existingin turbine operation and analogous operations.

The rust test used involves soaking a small disc of polishedsteel havinga slightly concave surfacein the oil under test at 90 F. for minutes,and thereafter placing a drop 01 distilled water below 'the surface ofthe oil 'and upon the surface of 'the steel disc. The test is thencontinued for 24 hours at 90F. At the end of the-latter periodthe steeldisrshould nothave' rust formed thereon in order that the oil pass" thetest; it rust has formed on the-disc during' this period, the'oil'underobservation fails the" test.

The emulsion test -used herein is the emulsion test for lubricatingoils(Method 320.13) described in the Federal Stock Catalog.'sectio1 1 IV.part 5, Federal Specifications VV-L-IQlb, February, 19; 1942. In thistest, 401:0.101'011' under observation and 40 cc. of emulsant;-eitherdistilled water or a 1% salt (NaCl) solutionaare stirred with a paddleat 1500 R. P. M. for Sminutes in a cc. cylinder at theprescribed-temperature of F. Separation of the emulsion formed thereinis observed while the cylinder is kept at the prescribed temperature fora specified time interval. Figures given in the chart provided in thecatalog identi-'- fled above are the actual minutes at which there is nocontinuous layeroi the emulsion remaining betweenthe oil and water; Withan oil having a viscosity similar to: that of the oil used in this test,specifications require that no continuous layer of emulsion remain atthe interface after a 30 minute period. Results of the aforesaid rustand emulsiontests are set 101111111 the table below. For' convenience anasterisk I) has been'used throughout the table tov indicate' those oilblends which have failed to pass one or both of the said tests and hasalsobeen used to designate those oil blends not contemplated by thepresent 'inven-' tion. I

A. Chemical Mixtures ,Emnlsion'lest oi2-cthylhuyholeyl l 1' filled 17 N01 I 9 n a gg, @255 mm Teat Wa'te'rf Solution gglg' Molesof m.- 101-(Minutes 101- complete c310! separation) Fail'....... 2 1 1 a0 0 20.00.0 .do 14 10 1.0 .4 220 0.2 23 .11. 1.4 0.0 220 .02. as. 15.. 1.2 0.821.0 0.2 20 17' 1.0 1.0 200 I 0.2- -22' 1a- 0.0 1.1 1&0 a2 10 2 0.8 1.220.0 0.2 20 2s- 01 1.3 11.0 0.2 22' 27; a0 1.1 10.0 0.2 3a 30. -0.0 1.51110 02 =32 20 0.4 1.0 1&0 0.2 --a9 -za- '0 '20 14.0 0.2 '42. -40

a. Pa l Mixtures Emulslon 'leut N Com I Distilled 1%Na0l :Dbhmyl moleEster percent Rust Test Water Solution hetlyl mizimfalo,

a mo 9 mo pet (Minutes for com plate percent cent separation) Fall-"ml 1100 0 .25.0 0.2v .d0.' 14 70 30 22.4 0.2 Pass. 24 Z! 40 60 20.6 0.2.do.... 27 30 G. (ilnmlcal mlxtilres Emulsion Test,

of 2-et11yl hexyl, octadecylmalate Di m d 0 at e 17 Na .1 l as z r 223;}Rust test water s lution Mole! 01 Males of p 2iethyil made: 1 (M1 mynutes lor c'ompleto alcohol 1 I .seporatlon);

- l 2 "1. 2.0 '0 25.0 0.2 14 10 I '1.8 0.2 24.0 0.2 21 1.0 0.4 22:0 0.2l 30 14 1.4 0..6 21.0 2 28 17' 1.3. 0.7K I 22.0 0.2; 23 27 1.0 1.0. 21.00.2' 23 .18 0.0 1.1 16.0 0.2 30 8' 0. 8 1. 2 23. 0 0. 2 23 2Q 0.6 1.420.0 0. 2

"n be. ofolnulalon after 1 hr. "'15 cc. of emulsion after 1 hr. ""13400. 01 emulsion after 1 hr.'..

w gl l w Emulsion Test mwhyl mocm fi' Con ci. mm Distilled 1% NaCl he!.decyl Ester per cent Test Water 1 Solution malalte, malalte, I

mo 9 mo 0 I (Minutes for comper cent. per cent plate s eparatlon) 70 an22.4 o. 2 '22 25 60 40 21. 7 0. 2 20 Z; b0 21. 2 0. 2 28 30 30 1 20. 30. 2 27 30 '20 19. 8 0. 2 '58 21 '10 '90 19.4 0. 2 36 "1 cc. of emulsionafter 1 hr. 134 on. o! amulaion after 1 hr.

B. Chemical Mixtures ofone mole of Emulsion ms mallcacld nnd- Dis- 7 b?Conc., Rust tilled ggi f Ester percent Test Water Mole; of Short- Moleaof bonfi-chaln Chain Alcohol Alooho (Mlnutealor'oom- V I plateaeparatlon) Falla. 1 i

1.0 n-he l 1 0 0 22. 0 0. 2 Pass 17 17 1.0 cycloexyL. .c 52.0 0.2 .do..18 30 1.0 n-ilepty 13.0 0. 2 .d0.. 13 14' 1.0 lnurgl. d 26.0 0.1 .do '48'45 1.0 2-el: y Lododecy 22.0 0.2 .do.. 24 11 Do... 1.0 7-ethyl-2methyl47.0 0.2 "do... 15 14 undecanol. Do... 1.0 hexa-decyl 20.0 0.2 .do... 2022 The data in section A o! the table above for the oil and for the oilblends containing 0.2% the various chemical mixtures of 2-ethyl hexyl,oleyl malate eflectiveiy demonstrates the superiority oi the oilcompositions contemplated herein. As shown in section A, the oil alonefails to pass the rust test, although the emulsion characterlsticsthereof are satisfactory. An oil blend containing di(2-ethyl hexyl)malate also fails to pass the rust test, yet has desirable emulsioncharacteristics. when the ester product blended in the oil is obtainedby reacting one molar equivalent of malic acid with irom about 0.7 toabout 1.6 molar equivalents of z-ethyl hexyl alecho] and with from about1.3 to about 0.4 molar equivalent of oleyl alcohol, the oil blends havedesirable rust and emulsion characteristics inasmuch as they readilypass both tests. Yet, when the ester product is obtained by reacting onemolar equivalent of malic acid with less than about 0.6 molar equivalentof 2-ethyl hexylalcohol and with more than about 1.4 molar equivalentsof oleyl alcohol, oil blends containing the same fail to pass theemulsion test, although they pass the rust test.

Oil blends containing physical mixtures of the malic acids obtained byblending dioleyl malate and di(2-ethyl hexyl) malate are shownv insection 13 of the table. The results provided therein indicate thateflec'tive blends are obtained with 40 through 70 mole per cent ofdi(2-ethyl hexyl) malate and with 70 through 30 mole per cent of dloleylmalate.

The results shown in section C of the table are similar to those shownin section A. in that the results for chemical mixtures of z-ethylhexyl, octadecyl malate have the same critical proportions, namely, tromabout 0.8 to about 1.6

molar equivalents of the short-chain alcohol, such as 2-ethyl hexyl, andfrom about 1.2. to

about 0.4 molar equivalent of the long-chain al- Section D of the tablecarries results of the said tests with oil blends f containing smallamounts otphysical mixtures;

cohol, such as octadecyl.

of dl'wtadecyl malate and M dim-ethyl fi i about; 0.4 molar equivalentof a long-chain alimalate. These results also indicate the eflectivephatic alcohol having between twelve and about ness of the ester mixturmum within the aforesaid critical limit or on compositions oontainiii gauo'aoid esters of the type contemplated herein along with an estermixture not contemplated-lauryl, oleyl malate-are shown in section E-oithe table. These results demonstrate the critical nature of the mixtureof the aliphatic groups: that is, that one such group shouldcontain fromsix to eight carbon atoms and another should containat least twelvecarbon atoms. For example, lauryl, oleyl malate contains one aliphaticgroup having twelve carbon atoms and another having eighteen carbonatoms and when blended in the oil does not pass the emulsion test.

The malic acid esters of this invention may be used in oils in amountsoi from about 0.1% to about 1.0% although preferred concentrations areof the order of 0.2% and 0.3%. They may also be used in largerconcentrations, of the order of 1% and greater, in cutting oilsand thelike.

These esters may also be used alone in oils and may also be used in oilscontaining one or more additives. For example, they may be used in oils,with oxidation inhibitors, film strength improving agents, oillnessagents, etc. Typical of such additives are the well known phenols,amines, sulfides, organic compounds containins phosphorus, organiccompounds containing haiogen, etc.

It is to be understood that although the invention has been illustratedhereinabove by certain preferred esters and oil blends of the same, it'is not to be restricted thereto but is to be broadly construed in thelight of the scope of the appended claims.

We claim:

1. A mineral oil composition comprising a viscous mineral oil having inadmixture therewith a minor proportion, sufiicient to impart antirustingcharacteristics to said oil, of an ester product of malic acid selectedfrom the group consistingpf: an ester product of malic acid obtained byreacting one molar equivalent oi malic acid with from about 0.8 to about1.6 molar equivalents of a short-chain aliphatic alcohol having from sixto eight carbon atoms and with from about 1.2 to about 0.4 molarequivalent of a long-chain aliphatic alcohol having between twelve andabout eighteen carbon atoms; and a mixture of esters ofmalic acid. oneof said esters having two short-chain aliphatic groups containing fromsix to eight carbon atoms substituted for the carboxylic hydrogen atomsof malic acid and said ester being present in the mixture in a molarquantity of from about forty to about eighty per cent, and another orsaid esters hav-. ing two long-chain aliphatic groups containing betweentwelve and about eighteen carbon atoms substituted for the carboxylichydrogen atoms of malic acid and said ester being present in the mixturein a molar quantity of from about sixty to about twenty per cent.

2. A mineral oil composition comprising a viscousminerai oil having inadmixture therewith a ing one molar equivalent of mallc acid with from aabout 0.8 to about 1.6 molar equivalents of a short-chain aliphaticalcohol having from six to e ht carbon atoms and with from about 1.2 to

' eighteen'carbon atoms; and a mixture of esters 10 hydrogen atoms ofmalic acid and said ester being present in the mixture in a molarquantity of from about forty to about eighty percent, and another ofsaid esters having two long-chain aliphatic groups containing betweentwelve and about eighteen carbon atoms substituted for the carboxylichydrogen atoms of malic acid and said ester being present in the mixturein a molar quantity of from about sixty to about twenty per cent.

3. A mineral oil composition comprising a viscous mineral oil normallypermitting rusting oi ferrous metal surfaces in the presence of water,having in admixture therewith a minor proportion, suillcient to retardsaid rusting, of an ester product of malic acid obtained by reacting onemolar equivalent of malic acid with from about 0.8 to about 1.6 molarequivalents of a shortchain aliphatic alcohol having from six to eightcarbon atoms and with from about 1.2 to about 0.4 molar equivalent of along-chain aliphatic alcohol having from twelve to eighteen carbonatoms.

4. A mineral oil composition comprising a via tion, suflicient to retardsaid rusting, oi an ester .product of malic acid obtained by reactingone molar equivalent of mallc acid with one molar one molar equivalentoi a long chain aliphatic alcohol having from twelve to eighteen carbonatoms. 7 I I v 5. A mineral oil composition comprising a viscousmincraloil normally permitting rusting oi ferrous metal surfaces in thepresence ofwater. having in admixture. th erewith, a minor proporrhydrogen atoms oi malic acid and said ester betion, sufllcienttor'etardssis"orsnester= .""ing' present "in the mixture in'a 'molarquantity 4 pd ct. at a a ob a ne byresa ils on molar-equivalent oi. inallc' acidwithfrom about;

0.8 to about 1.6.molar equivalents of 2-ethyl hexyl' alcohol andwithironi nbout lj to about 0.4 molar equivalent or oleylalcohol.

s. Amman ollf'co pbsition coinprlsing cous mineral oil normallypermitting rusting'oi ferrous metal surfaces in the "presencool' Water.having in admixture therewith a minor proportion, sufilcientto retardsaid jrustin'mbian ester product] of malic acidobtainedby reacting onemolar Iequivalentoi malic with from about 0.8 to about 1.6 molarequivalents oi Q-ethyl 0.4 molar equivalent or octadecyl alcohol.

having in admlxture'therewith 'a minor proportion, sufficient to retardsaid rusting, of an ester product of'malic acid, obtained by reactingone molar equivalent oi' mallc acid with from about 0.8 to about 1.'o'molar-;equivalent o! fl-ethyi hexyl alcohol and with from about 1.2 toabout 0.4 molar equivalentoi hexadecyl alcohol.

8.- A mineral oil composition comprising a viscous mineraloil'riorinally permitting rusting of ferrous metalsuriacesj in thepresence of water. having iii-admixture therewith a minor propor'- tion,sufiicient to retard said rusting, 0! a mix! ture of esters ormalic'acid,uone of said esters having two short-chain aliphatic groupscontaining rromsixto-eightcarbon atoms substituted for the carboxyliohydrogen atoms oi malic acid and said esterbeing present in the mixturein a molar quantity or from about 'iortyto about eighty-2 per cent, andanother of said esters having two long-chain aliphatic groups containingiromtwelve to eighteen carbon atoms substituted for the carboxylichydrogen atoms of malic acid and said ester beingpresent intheinixturein a molar quantity or irom about sixty to about v twentynerce t,

ad'r'i'iixtfirtlierewith sis-minor.v propel-e.

.. minor'proportiom at least about 0;

more O I. mineral oil composition comprising 5Y1! taining from-six toeight carbon atoms substituted for the carboxylle hydrogen atoms ofmalic 1. acid and said ester being present in the mixture in a molarquantity of about fifty per cent, and

another of said esters having two long-chain aliphatic groups containingfrom twelve to eightof about iiity'per cent. o

10. A mineral oil composition comprising aviscous mineral oil having inadmixture therewith a of an ester product of malic acids the groupconsisting'oi: an ester product-o! malic acid obtained by reacting onemolar equivalent of. 'mallcacid with iromaboutuafto about 1.8 molar aequivalents of a short-chain aliphatic alcohol having from six to eightcarbon atoms angi wlm.v i from about 1.2 to about 0.4 molarequivalent'ot a long-chain aliphatic alcohol having. between twelve andabout eighteen carbon atoms; and a. a ,mixtureoi esters oi-malic acid,one or saidesters having two short-chain aliphatic groups contain :1.in! 1mm slx to'eight'carbonatoms substituted 7 tor the carboxylic'hydrogenatoms oi malic'acld 1 and said ester being present in themixture in a as molar quantity of'irom about forty to about eighty percent, and another of said "esters having two long-chain aliphatic groupscontaining between twelve .and about; eighteen carbon atoms substitutedfor the carboxylic hydrogen 40 atoms of malic acid and said ester beingpresent i. in the mixture in a molar quantity of i'r'om about sixty toabout twenty per cent. a GEORGE E. S. SNYDER.

RALPH V. WHITE.

r JOHN H. manor.

v Joann soconor'smr. REFERENCES err-an 'tmrrnn sums m'mm's Number NameDate.

1,993,186 Graves Mar. 12, 1935 2.101.221 wet-nu Dec. 1, mar 2,210,200 l'arrington Feb.27,1946 ,zsvosoo Farrington Feb.2'l.1945 Blair, Jr. Maya, 1m

neral "oil norma lyv Permittingjrustingf or ferrous .metal surfacesinithe presenceoi water.

can carbon atoms substituted for the carboxylio' Certificate ofCorrection Patent No. 2,436,272. Februery 17,1948.

GEORGE H. S. SNYDER ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Column 7,line 64, for 0.1% read 0.01%; and that the said Letters Patent should beread with this correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 4th day of May, A. D. 1948.

THOMAS F. MURPHY,

Assistant Commissioner 0 Patents.

Certificate of Correction Patent No. 2,436,272. February 17,1948;

GEORGE H. S. SNYDER ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Column 7,line 64, for 0.1% read 0.01%; and that the said Letters Patent should beread with this correction therein that the same may conform to therecord of the case in the Patent Ofiice.

Signed and sealed this 4th day of May, A. D. 1948. 7

THOMAS F. MURPHY,

Assistant Gommz'sst'oner of Patents.

